Dried blood spot sampling for therapeutic drug monitoring: challenges and opportunities

ABSTRACT

Introduction

The use of dried blood spots (DBS) has gained interest in the field of therapeutic drug monitoring (TDM) due to its potential advantages, such as minimally invasive capillary blood collection, potential stabilization of drugs and metabolites at room or high temperatures, and lower biohazard, allowing for inexpensive storage and transportation. However, there are several drawbacks to the clinical use of DBS in TDM, mostly related to hematocrit (Hct) effects, differences between venous and capillary blood concentrations, among others, that must be evaluated during analytical and clinical method validation.

Area covered

This review focuses on the most recent publications on the applications of DBS sampling for TDM (2016–2022), with a special focus on the challenges presented by this alternative sampling strategy, as well as the opportunities for clinical applications. Real-life studies presenting clinical applications were reviewed.

Expert opinion

With the availability of method development and validation guidelines for DBS-based methods in TDM, higher levels of assay validation standardization have been achieved, expanding the clinical applications of DBS sampling in patient care. New sampling devices that overcome the limitations of classical DBS, such as the Hct effects, will further encourage the use of DBS in routine TDM.

KEYWORDS:

• Dried blood spots
• therapeutic drug monitoring
• microsampling
• capillary sampling devices
• alternative sampling

Article highlights

• Dried blood spot (DBS) collection through finger pricking empowers patients to obtain blood samples at home, enabling analysis for diagnostic purposes.

• Addressing the influence of hematocrit levels and implementing rigorous analytical validation is a crucial step toward enhancing the accuracy and reliability of DBS-based clinical laboratory testing,

• Recent microsampling devices enable volumetric capillary blood collection regardless of hematocrit levels.

• DBS sampling provides a convenient and accurate alternative for therapeutic drug monitoring (TDM) in clinical practice.

• Capillary microsampling strategies such as DBS will become increasingly relevant for TDM and laboratory medicine.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants, or patents received or pending, or royalties.

Reviewer declarations

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was funded by Conselho Nacional de Desenvolvimento Científico e Tecnológico (309453/2022-4).